Changed standard encoding to use host endianness. Engine roll.

This patch covers multi-box adaptor and the viewports.

Provides a strong hint to developers that editing Flutter framework
headers isn't supported.

It was resulting in weird situations where the tool would dump an
error message and stack but not quit, or would fail hard but then just
hang.

Instead, specifically catch errors you expect. As an example of this,
there's one error we expect from the DartDependencySetBuilder, so we
catch that one, turn it into a dedicated exception class, then in the
caller catch that specific exception.

Most of these docs were already in place, but this patch adds the remaining
missing ones.

Fixes #8618

Also, some renames for more accuracy.

* do not forward status if stream is closed
* remove devfs test timeout

Add the minimum set of required properties for run_recipe.py and where
to look them up.

These symbols were not intended to be public. Also, remove some bogus dartdocs
for PhysicalModeLayer.

(follow-on to #8698)

Windows' built-in unzippers are painfully slow. It drives me mad!

Unzip SDK with 7-Zip: ~10s
Unzip SDK with Windows: ~90s

Changing to an inline function, making the type more clear.

* Rename `Device.platform` to `Device.targetPlatform` to avoid
  collision with the exported variable from `platform.dart`

`all.dart` is no longer needed. Furthermore, it causes tests to
be skipped, or to silently fail to run anything.

Fixes #7941

Use line-based iteration in place of word-based iteration over the
framework directories, to avoid breaking on spaces.

* Revert "Eliminate CocoaPods install step (#8694)"

This reverts commit f4a13bc7.

If the developer is relying on CocoaPods and hasn't done a pod install, we will do it for them. This is needed for a smooth native plugin experience, similar to what Gradle is doing on the Android side.

There's no hard dependency on CocoaPods. We only run pod install if the project uses CocoaPods, so developers are still free to use alternatives if they prefer (and if they don't want to use native plugins).

Fixes #8685
Fixes #8657
Fixes #8526

* Require CocoaPods 1.0.0 or newer.

And make sure we don't get a crash if running `pod install` fails.

* Address review feedback

This avoids unintentionally installing an older version if the
developer's homebrew installation is out-of-date.

The flutter tap was deleted as part of the resolution to #7783.

If the developer is relying on CocoaPods and hasn't done a pod install,
they'll get a build failure indicating the issue.

This also avoids a hard dependency on CocoaPods in the tool and allows
developers to customize their Xcode steps to use alternatives such as
Carthage if they prefer.